The long term objective of this research is to develop a comprehensive multivariate theory of acute adverse reactions to psychoactive drugs that will have predictive as well as explanatory capacities. Specific aims of this research are to: (1) conduct an exploratory interview study of subjects who have experienced acute adverse reactions to psychoactive drugs in order to develop hypotheses about situational and setting determinants of these reactions, (2) further develop measures of acute adverse reactions, (3) develop a comprehensive questionnaire which will include operational measures of those elements of situational, set, and personality variables related to the development of acute adverse reactions, and exploratory hypotheses concerning long term effects of these reactions, and (4) to develop a series of theoretical mathematically stated models of increasing complexity that will specify the relative importance of factors related to the development of acute adverse reactions. The most comprehensive model that can be derived from this cross sectional data will be used as the initial model in the first phase of a longitudinal study. BIBLIOGRAPHIC REFERENCES: Naditch, M. P. Ego functioning and acute adverse reactions to psychoactive drugs. Journal of Personality, 1975, 43, 314-329. Naditch, M. P. Ego mechanisms and marijuana usage. Paper presented at Drug Lifestyles Conference, National Institute on Drug Abuse, January 22-24, 1975.